The present invention relates to a split yarn of a vinylidene fluoride resin, a process for production thereof and a filter comprising the split yarn.
From a vinylidene fluoride resin, a filament yarn which is made of continuous fiber has been commercially produced, whereas a split yarn or slit yarn which is made of staple form fiber has not been commercially produced.
Not only from a vinylidene fluoride resin, but also from many other resins, it is difficult to obtain a split yarn. A polypropylene yarn which is obtained by cold-stretching a polypropylene film at a high stretching ratio of around 10 times and splitting the stretched film has been known as a split yarn. However, no split yarn has been obtained in a similar manner from any other resin. This may be attributable to the fact that polypropylene has a high crystallinity and also has a weak cohesion strength so that the above described process is readily applicable thereto. For this reason, it has been considered difficult to obtain a split yarn from a vinylidene fluoride resin which has a low crystallinity and a larger intermolecular cohesion strength by the splitting process as described above.
A vinylidene fluoride resin however is a polar polymer and has a weather resistance and a chemical resistance which are essentially better than those of polypropylene. Accordingly, if a split yarn thereof can be obtained, it is expected be a useful functional material. Especially, if the split yarn of a vinylidene fluoride resin is obtained in an electrically charged state, it would be an excellent filter material retaining its charge stably.